This output type allows you to control a state of selected and configured outputs. When you change the state of the “Group switch” output, it reflects on all grouped outputs. So, you can control several outputs by one command.
In the “Limit switch” mode, you can send any signal to the “Group switch” output, and the firmware switches off all grouped outputs. It is useful, if you linked this output with an alarm input (for example, with a water leak sensor).